Abstract
Compression mouldings of commercial SMC were performed with an instrumented industrial press under various process conditions. Results underline the influence of process parameters such as the initial SMC temperature, the axial punch velocity and the geometry of the mould on local normal stress levels. They also show negligible fibre-bundle segregation in the principal plane of the moulded parts. Thereby, a one-phase plug flow shell model is proposed as a direct extension of the plug flow model proposed by M.R. Barone and D.A. Caulk [J Appl Mech 53(191):1986;361–70]. In the present approach, the SMC is considered as a power-law viscous medium exhibiting transverse isotropy. The shell model is implemented into a finite element code especially developed for the simulation of compression moulding of composite materials. Simulation and experimental results are compared, emphasizing the role of the SMC rheology on the overall recorded stress levels. Despite the simplicity of the model, rather good comparisons are obtained.
Highlights
Compression moulded composites such as sheet moulding compounds (SMC) or alternatively glass mat thermoplastics (GMT) are widely and increasingly used in different industry branches to produce thin semi-structural parts
Experimental results have underlined the influence of the position of the stack charge in the mould, its initial temperature as well as the axial punch velocity on recorded local normal stress levels
From the experimental results obtained previously in the literature and those gained in this work, a one-phase plug flow shell model was formulated, extending the plug flow model initially proposed in [6]
Summary
Compression moulded composites such as sheet moulding compounds (SMC) or alternatively glass mat thermoplastics (GMT) are widely and increasingly used in different industry branches to produce thin semi-structural parts. A second group of descriptions adopt the ‘‘plug flow’’ approximation, characterized by (i) a uniform in-plane shear and elongational deformation (ii) the absence of out of plane shear in the core of the stacked sheets and (iii) possible sheared boundary layers near the surface of the cavity This second type of deformation mechanism has given rise to one-phase plug flow shell models [6,5,34]. The main objectives of the present contribution are (i) to propose a plug flow model following the pioneering work of Barone and Caulk [6] and using a rheological model able to capture the effect of strain rate, temperature, bundle content and orientation on the mechanical response of the SMC, (ii) to test its capability to reproduce compression experiments performed in industrial conditions, and (iii) to implement it in a specially designed simulation code. A finite element (FE) formulation of the developed shell model is proposed and implemented in a FE application, allowing a comparison between experimental and numerical results (Section 5)
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